A multifunction peripheral, which has a plurality of functions such as a copying function, a scanning function, a printing function, and a fax sending/receiving function, has conventionally been known. In recent years, such a multifunction peripheral is connected with a control server (application server), or the like via a communication network so as to carry out various kinds of processes. Specifically, the multifunction peripheral serves as a part of a total application system in which the multifunction peripheral functions in cooperation with application software (hereinafter, simply referred to as “application”) which is operated on the control server. This makes it possible to easily establish a flexible system in which the functions of the multifunction peripheral and the functions of the control server appropriately cooperate with each other.
In such a system, the application in the control server transmits a control command to the multifunction peripheral so that a web server of the multifunction peripheral carries out a process corresponding to the control command. In other words, the functions of the multifunction peripheral are controlled by the application in the control server.
Moreover, in view of security maintenance, the multifunction peripheral as described above is sometimes set to execute a control command supplied from a highly reliable application (i.e., an application developed by a highly reliable vendor) but to prohibit execution of a control command received from a hardly-reliable application. For example, there is a method in which a control command, which contains a security identifier (e.g., a vendor key) indicative of a validity of the control command, is transmitted from an application to a multifunction peripheral, and then, on the multifunction peripheral side, whether or not to execute the control command is judged by checking the validity of the security identifier contained in the received control command.
In the method, however, the security identifier is transmitted via a communication path. In view of this, in a case where communication data can be intercepted in the employed communication path, it is necessary to encrypt the communication data (e.g., a control command) by using an encryption protocol such as an SSL (Secure Socket Layer). This causes a problem that the method cannot be applied to an application which cannot carry out a process using the encryption protocol.